1. Field of the Invention
The present invention relates to a door damper, and electronic appliances having the same. More particularly, the present invention relates to a door damper, which enables a door to be smoothly opened while relieving impact when the door is opened, and electronic appliances having the same.
2. Description of the Related Art
Generally, electronic appliances such as dish washing machines or microwave ovens have a receiving compartment to receive an object, and a hinged door coupled to a front side of the receiving compartment to open or close the receiving compartment. Since the hinged door is hingably coupled to a body of the appliance via a hinge device, it is advantageous to widely open an entrance of the receiving compartment and to maintain sealing of an opening/closing part after closing the door.
However, such a hinged door has a problem in that, when a user opens the door with great force or opens the door rapidly, an impact can be applied to one side of the hinge device to cause noise, and in some cases, can cause damage to the hinge device. In particular, in the case where the door is opened downwardly as with a typical microwave oven, the problem becomes severe due to the weight of the door. Accordingly, most electronic appliances employing a hinged door are provided with a door damper to relieve the impact occurring when the door is opened.
One example of a door damper is disclosed in Korean Patent No. 1995-10686, entitled “Multi-plate type damper using viscous fluid.” The door damper of the disclosure includes a plurality of movable plates rotatably equipped to a rotational shaft within a casing, a plurality of stationary plates disposed between the movable plates within the casing, and viscous fluid filled between the stationary plates and the movable plates within the casing to generate rotating resistance to the movable plates. The rotational shaft extends to the outside of the casing, and is coupled to the door. This structure can generate rotating resistance to the rotational shaft to relieve an impact occurring when the door is opened or closed.
However, although the door damper of the disclosure can relieve the impact occurring when the door is opened or closed, there is a problem in that, since rotating resistance is continuously applied to the rotational shaft from an initial stage of opening the door to a final stage of completely opening the door, and vice versa, the door cannot be smoothly opened or closed, causing inconvenience.